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<p>Dear Michal,</p>
<p><br>
</p>
<p><span style="color:rgb(33,33,33); font-family:wf_segoe-ui_normal,"Segoe UI","Segoe WP",Tahoma,Arial,sans-serif,serif,EmojiFont; font-size:13.333333015441895px">> @Iurii: the motivation (or rather - hope) is that TDDFT (or</span><br style="color:rgb(33,33,33); font-family:wf_segoe-ui_normal,"Segoe UI","Segoe WP",Tahoma,Arial,sans-serif,serif,EmojiFont; font-size:13.333333015441895px">
<span style="color:rgb(33,33,33); font-family:wf_segoe-ui_normal,"Segoe UI","Segoe WP",Tahoma,Arial,sans-serif,serif,EmojiFont; font-size:13.333333015441895px">> perhaps even epsilon.x) will give us the correct trend, whilst being</span><br style="color:rgb(33,33,33); font-family:wf_segoe-ui_normal,"Segoe UI","Segoe WP",Tahoma,Arial,sans-serif,serif,EmojiFont; font-size:13.333333015441895px">
<span style="color:rgb(33,33,33); font-family:wf_segoe-ui_normal,"Segoe UI","Segoe WP",Tahoma,Arial,sans-serif,serif,EmojiFont; font-size:13.333333015441895px">> much cheaper than GW/BSE (which we are trying as well).</span><br>
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<p><br>
</p>
<p>You can try to use the turboEELS code with a very small transferred momentum q. The code prints at the end the loss function -Im[1/eps(w,q)] but also Im[eps(w,q)]. In the long wavelength limit Im[eps(w,q->0)] gives you the optical absorption spectrum at
the TDDFT level in the adiabatic approximation with a LDA/GGA functional (see e.g. Fig. 3 in Comput. Phys. Commun. 196, 460 (2015)).</p>
<p><br>
</p>
<p>Best,</p>
<p>Iurii</p>
<p><br>
</p>
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<font size="3" face="'Times New Roman', Times, serif" color="808080">--<br>
Dr. Iurii Timrov<br>
Postdoctoral Researcher<br>
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<font size="3" face="'Times New Roman', Times, serif" color="808080">STI - IMX <font color="808080">
<font face="'Times New Roman', Times, serif">- THEOS</font></font></font><font size="3" face="'Times New Roman', Times, serif" color="808080"> and NCCR - MARVEL<br>
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<font size="3" face="'Times New Roman', Times, serif" color="808080"><font size="3" face="'Times New Roman', Times, serif" color="808080">Swiss Federal Institute of Technology Lausanne (EPFL<font color="808080"><font face="'Times New Roman', Times, serif">)</font></font></font><br>
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<font size="3" face="'Times New Roman', Times, serif" color="808080">CH-1015 Lausanne, Switzerland<br>
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<div id="x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> users <users-bounces@lists.quantum-espresso.org> on behalf of Michal Krompiec <michal.krompiec@gmail.com><br>
<b>Sent:</b> Wednesday, April 15, 2020 7:54:32 PM<br>
<b>To:</b> Quantum ESPRESSO users Forum<br>
<b>Subject:</b> Re: [QE-users] safe to enable "k-point algorithm" in turbo_lanczos?</font>
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<div class="PlainText">Dear Oleksandr, Dear Iurii,<br>
Thank you very much, I understand that this code should rather stay<br>
disabled. @Iurii: the motivation (or rather - hope) is that TDDFT (or<br>
perhaps even epsilon.x) will give us the correct trend, whilst being<br>
much cheaper than GW/BSE (which we are trying as well).<br>
Best,<br>
Michal<br>
<br>
On Wed, 15 Apr 2020 at 18:39, Oleksandr Motornyi<br>
<oleksandr.motornyi@polytechnique.edu> wrote:<br>
><br>
> Dear Michal,<br>
><br>
><br>
> The k-points algorithm of turbo_lanczos.x as it is does not give the correct results if there is more than one single k-point. However you can look up the Lanczos implementation in the thermo_pw module, which works fine with k-points as far as I remember
(of course bare in mind what Iurii said about Adiabatic TDDFT).<br>
><br>
><br>
> Regards,<br>
><br>
> Oleksandr<br>
><br>
> On 15/04/2020 19:35, Timrov Iurii wrote:<br>
><br>
> Dear Michal,<br>
><br>
><br>
> The k-points implementation of turbo_lanczos.x was not tested and hence it is disabled. But most importantly, very likely there are bugs (I think I know a few). Someone has to work on it and fix bugs. But is there a motivation to do so? Adiabatic TDDFT with
LDA/GGA is known to be not accurate for the optical absorption spectroscopy of solids.<br>
><br>
><br>
> Greetings,<br>
><br>
> Iurii<br>
><br>
><br>
> --<br>
> Dr. Iurii Timrov<br>
> Postdoctoral Researcher<br>
> STI - IMX - THEOS and NCCR - MARVEL<br>
> Swiss Federal Institute of Technology Lausanne (EPFL)<br>
> CH-1015 Lausanne, Switzerland<br>
> +41 21 69 34 881<br>
> <a href="http://people.epfl.ch/265334">http://people.epfl.ch/265334</a><br>
> ________________________________<br>
> From: users <users-bounces@lists.quantum-espresso.org> on behalf of Michal Krompiec <michal.krompiec@gmail.com><br>
> Sent: Wednesday, April 15, 2020 7:26:09 PM<br>
> To: Quantum Espresso users Forum<br>
> Subject: [QE-users] safe to enable "k-point algorithm" in turbo_lanczos?<br>
><br>
> Hello,<br>
> I'm trying to compute the spectrum of a crystalline insulator using<br>
> turbo_lanczos. I got the following error:<br>
><br>
> Error in routine lr_readin (1):<br>
> k-point algorithm is not tested yet<br>
><br>
><br>
><br>
> I guess I could just comment line 477 out in TDDFPT/src/lr_readin.f90<br>
> to disable this error:<br>
><br>
> ! K-points are implemented but still unsupported (use at your own risk!)<br>
> !<br>
> IF (.NOT. gamma_only ) CALL errore('lr_readin', 'k-point<br>
> algorithm is not tested yet',1)<br>
><br>
> But how unstable is this code? Any reason not to try this?<br>
><br>
> Thanks,<br>
><br>
> Michal Krompiec<br>
> Merck KGaA<br>
> _______________________________________________<br>
> Quantum ESPRESSO is supported by MaX (<a href="http://www.max-centre.eu/quantum-espresso">www.max-centre.eu/quantum-espresso</a>)<br>
> users mailing list users@lists.quantum-espresso.org<br>
> <a href="https://lists.quantum-espresso.org/mailman/listinfo/users">https://lists.quantum-espresso.org/mailman/listinfo/users</a><br>
><br>
> _______________________________________________<br>
> Quantum ESPRESSO is supported by MaX (<a href="http://www.max-centre.eu/quantum-espresso">www.max-centre.eu/quantum-espresso</a>)<br>
> users mailing list users@lists.quantum-espresso.org<br>
> <a href="https://lists.quantum-espresso.org/mailman/listinfo/users">https://lists.quantum-espresso.org/mailman/listinfo/users</a><br>
><br>
> --<br>
> Oleksandr Motornyi<br>
> PhD candidate<br>
><br>
> Laboratoire de Solides Irradies<br>
> Ecole Polytechnique (Palaiseau, France)<br>
><br>
> _______________________________________________<br>
> Quantum ESPRESSO is supported by MaX (<a href="http://www.max-centre.eu/quantum-espresso">www.max-centre.eu/quantum-espresso</a>)<br>
> users mailing list users@lists.quantum-espresso.org<br>
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